Tony Klasing, Manager
Vehicle Inspection Unit
Division of Traffic Safety
Illinois Department of Transportation
3215 Executive Park Drive
P. O. Box 19212
Springfield, IL 62794-9212
Dear Mr. Klasing:
This responds to your request for an interpretation of Federal Motor Vehicle Safety Standard No. 217, Bus emergency exits and window retention and release. Specifically, you wish to know whether in test procedures for school buses specified at S220.127.116.11(a)(1) of the standard, a parallelepiped is used or a template. The answer is the agency uses a parallelepiped, as specified in the standard, rather than simply measuring from the rear of the seat back to the exit door.
As specified at S18.104.22.168(a), the rear emergency exit door must be manually extendable by a single person to a position that permits "an opening large enough to permit unobstructed passage of a rectangular parallelepiped 114 centimeters high, 61 centimeters wide, and 30 centimeters deep" when "keeping the 114 centimeter dimension vertical, the 61 centimeter dimension parallel to the opening, and the lower surface in contact with the floor of the bus at all times."![endif]>![if>Contrary to what may be your understanding, the agency has not "approved" the use of a template that tapers at the top.
I hope this information is helpful. If you have any further questions, please feel free to contact Dorothy Nakama of my staff at this address or at (202) 366-2992.
![endif]>![if> In some school buses, the rear of the bus may curve inward, towards the passenger compartment. In such cases, in testing, although the bottom of the parallelepiped is in contact with the floor of the bus at all times, the top part of the parallelepiped may extend outside of the bus. When it conducts its school bus compliance testing for the rear emergency exit door, NHTSA would deem the school bus to meet S22.214.171.124(a)(1) of Standard No. 217 as long as the bottom of the specified parallelepiped is in contact with the floor of the bus at all times.